EMPIRE-1 Phase 2/3 Trial Results Indicate Fluorine 18 Fluciclovine PET/CT Utilization May Confer Event-Free Survival Advantage

Prostate cancer is the second most common cancer in men and will affect approximately 248,530 Americans in 2021.¹ The disease is typically diagnosed in men aged >65 years, with an average age at diagnosis of 66 years.¹ Digital rectal examination, prostate-specific antigen (PSA) levels, and medical history may suggest the patient has prostate cancer and imaging is used to confirm the diagnosis.² Molecular imaging is increasingly being used to plan and guide disease treatment with clinical trials being used to evaluate this type of imaging.³ In the May 2021 edition of Lancet, Jani and colleagues published findings from the EMPIRE-1 phase 2/3 trial that compared the use of fluorine 18 fluciclovine positron emission tomography/computed tomography (PET/CT) with conventional bone scan and magnetic resonance imaging or CT imaging alone to guide salvage postprostatectomy radiotherapy in patients with prostate cancer.

In this single-center, open-label study, 165 patients who had a detectable PSA after prostatectomy and no bone or metastatic lesions found with conventional imaging, were randomly placed into cohorts to receive either radiotherapy directed by conventional imaging or with fluorine 18 fluciclovine PET/CT imaging combined with conventional imaging. PSA concentration, androgen deprivation therapy intent, and radiotherapy decisions were considered for randomization into the cohorts. There were 4 patients in the fluorine 18 fluciclovine PET/CT group who had to have radiotherapy discontinued. These patients were not included in the survival analysis.

In the group receiving fluorine 18 fluciclovine PET/CT radiotherapy, decisions and target delineation were determined by PET findings. The study's primary end point was 3-year event-free survival (EFS) with a study median follow-up of 3.52 years (95% confidence interval [CI], 2.98-3.95 years). Events were defined as initiation of systemic therapy, disease progression, or clinical or biochemical recurrence of disease. In the conventional imaging group, 33% of 81 patients had events with a 3-year EFS of 63% (95% CI, 49.2-74.0). The fluorine 18 fluciclovine PET/CT group had 20% of 76 patients experiencing events with a 3-year EFS of 75.5% (95% CI, 62.5-84.6). Adverse events were reported in both groups. Late urinary frequency or urgency was reported in 31 patients in the fluorine 18 fluciclovine PET/CT group and 37 patients in the conventional imaging group. Acute diarrhea occurred in 16 patients in the fluorine 18 fluciclovine PET/CT group and 11 patients in the conventional imaging group. Upon further analysis, the researchers found that study group participation was significantly associated with EFS from biochemical recurrence or persistence.

References

1. American Cancer Society. Key statistics for prostate cancer. Updated January 12, 2021. www.cancer.org/cancer/prostate-cancer/about/key-statistics.html. Accessed September 20, 2021.
2. American Cancer Society. Tests to diagnose and stage prostate cancer. Updated June 10, 2021. www.cancer.org/cancer/prostate-cancer/detection-diagnosis-staging/how-diagnosed.html. Accessed September 20, 2021.
3. Jani AB, Schreibmann E, Goyal S, et al. 18F-fluciclovine-PET/CT imaging versus conventional imaging alone to guide postprostatectomy salvage radiotherapy for prostate cancer (EMPIRE-1): a single centre, open-label, phase 2/3 randomised controlled trial. Lancet. 2021;397:1895-1904.